Optical fiber bend sensor

A temperature sensor comprising:

• a fibre assembly including a multicore optical fibre having component cores sufficiently separated to counteract crosstalk and a sensor length section;
• coupling means for coupling radiation propagating in a first core of said component cores into a second core of the component cores of the fibre assembly;
• reflecting means for reflecting a portion of incident radiation, said reflecting means and said coupling means arranged such as to define a first optical path corresponding to radiation propagating within said first core and a second optical path corresponding to radiation propagating within said second core, wherein said paths have an optical path difference over said sensor length section;
• and
• analysing means for analysing radiation output from the fibre assembly and developing and spectrally dispersing interferograms formed between the radiation propagating in the first and second optical paths and for providing a temperature output determined from phase variations in said interferograms.

A bend sensor comprising:

• a fibre assembly including a multicore optical fibre having component cores sufficiently separated to counteract crosstalk and a sensor length section;
• a coupler coupling radiation propagating in a first core of said component cores into a second core of the component cores of the fibre assembly;
• reflectors reflecting a portion of incident radiation, said reflectors and said coupler arranged such as to define a first optical path corresponding to radiation propagating within said first core and a second optical path corresponding to radiation propagating within said second core, wherein said paths have an optical path difference over said sensor length section;
• and
• an interferometric analyser analysing radiation output from the fibre assembly and developing and spectrally dispersing interferograms formed between the radiation propagating in the first and second optical paths and for providing a fibre curvature output determined from phase variations in said interferograms.

A temperature sensor comprising:

• a fibre assembly including a multicore optical fibre having component cores sufficiently separated to counteract crosstalk and a sensor length section;
• a coupler coupling radiation propagating in a first core of said component cores into a second core of the component cores of the fibre assembly;
• a reflectors for reflecting a portion of incident radiation, said reflectors and said coupler arranged such as to define a first optical path corresponding to radiation propagating within said first core and a second optical path corresponding to radiation propagating within said second core, wherein said paths have an optical path difference over said sensor length section;
• and
• an interferometric analyser analysing radiation output from the fibre assembly and developing and spectrally dispersing interferograms formed between the radiation propagating in the first and second optical paths and for providing a temperature output determined from phase variations in said interferograms.

A method of sensing a bend in an optical fibre, said method comprising the steps of:

• providing a multicore optical fibre having component cores sufficiently separated to counteract crosstalk and a sensor length section;
• coupling radiation propagating in a first core of said component cores into a second core of the component cores of the fibre assembly;
• reflecting a portion of incident radiation, said reflecting step and said coupling step arranged such as to define a first optical path corresponding to radiation propagating within said first core and a second optical path corresponding to radiation propagating within said second core, wherein said paths have an optical path difference over said sensor length section;
• and
• analysing radiation output from the optical fibre and developing and spectrally dispersing interferograms formed between the radiation propagating in the first and second optical paths and for providing a fibre curvature output determined from phase variations in said interferograms.